Can you not have a go at it yourself? - not a difficult job to remove and install a new engine.
I have removed mine a number of times with just basic tools and a trolley jack by myself
Great way of learning about your bus and engine
There are several articles online that explain it all but basically it involves the following
Jack up rear of the bus
Position on axle stands
Remove oil bath airfilter
Remove and clamp fuel lines to carb from tank
Label and disconnect battery and wiring (alternator/carb/coil/oil pressure switch and so on)
Disconnect throttle cable and push through fan housing hole
Remove rear valence
Position a jack under the gearbox mount and support the engine/gearbox
Remove 3 x engine moustache bar bolts
Jack engine & gearbox up enough to remove engine support bar from bus
Lower engine/gearbox enough to get access to the 2 upper attachment bolts (starter motor and behind the fan shroud)
Raise gearbox and position an axle stand underneath to hold it secure and level
Now position the jack under engine, support the weight and remove the 2 remaining gearbox attachment nuts
The engine can now be pulled to the rear, released from the gearbox and lowered out of the rear of the bus
Swap over ancillaries for your new engine, tinware/dizzy/carb/clutch/pressure plate and so on then refit
Whilst doing this you can renew the clutch release bearing or upgrade it to a late bay version, change the gearbox oil and fuel filter and have a good look around the engine bay for any other issues. Many replace their fuel lines if the old ones are in an unknown condition or not R9 spec
Easily done in a day or if you are taking it nice and easy over a weekend from start to finish
Doing it yourself will give you confidence and a better understanding of how it all goes together
If you do get stuck there are always peeps on here who would be able to help
